1. Field Of The Invention
The present invention relates to a pressure vessel having an elastic bladder for evacuating the fluids contained inside the vessel. More particularly, the invention relates to a cap which secures the bladder of a pressure vessel to a spout or neck portion disposed around an opening in the vessel. This cap also allows access to the bladder so that the user may inflate the bladder and evacuate the vessel.
2. Description Of The Prior Art
The prior art includes many pressure vessels which have a bladder disposed in the chamber defined by the vessel. In some of these prior vessels the bladder acts as a liner and receives the fluids which the vessel contains. In other prior pressure vessels the bladder forces the fluids which the vessel contains out of the vessel as the user fills the bladder with a second fluid, normally a gas.
These prior art pressure vessels include various structural components which secure the bladder to the shell of the vessel so that the user of the vessel may have access to the bladder and which provide communication between the outside of the vessel and the bladder. These prior vessels, however, suffer a number of disadvantages. First, the components used to secure the bladder require that the pressure vessel have a substantially increased thickness at the location where they secure the bladder to the vessel. Additionally, the structural components are massive and include a multiplicity of close tolerance components which are costly and difficult to assemble. Finally, they do not fasten the bladder securely; and they do not provide leak-proof communication with the bladder.
The pressure vessel of the present invention provides a structure which overcomes the disadvantages and complexities of the prior art. It includes a bladder with a securing structure which has a small number of components with sufficiently accurate and consistent tolerances to provide leak-proof communication between the outside of the vessel and the inside of the bladder. This structure also provides the requisite clamping action to effectively secure the bladder to the shell of the vessel.
The pressure vessel of the present invention comprises a shell made of a thermoplastic inner liner and a filament wound outer layer. This shell has an opening, and a sleeve portion or spout disposed circumjacent this opening. The cap which closes this opening secures a bladder disposed inside the vessel to the spout and allows access to the inside of the bladder so that the user may fill the bladder with a fluid, namely a gas such as air. As the bladder expands, it displaces the liquid fluid which the vessel contains and forces it out of the vessel through a port.